Due to the requirements of application scenarios, a wireless transmission apparatus needs to be installed on a roof or tall tower and needs treatments such as waterproofing, so the installation and disassembly is complex. When a system fault occurs in the wireless transmission apparatus, to reduce operations of disassembling and installing the wireless transmission apparatus, the wireless transmission apparatus usually needs to have an independent loopback channel established inside or a loopback device externally connected to perform self-checking. However, the inside establishment of the independent loopback channel in the wireless transmission apparatus increases additional cost and design complexity, and the external connection of the loopback device requires engineering personnel to work on site and has poor operability.